Screaming cowbird

Last updated

Screaming cowbird
Screaming Cowbird (Molothrus rufoaxillaris).jpg
Screaming cowbird song
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Passeriformes
Family: Icteridae
Genus: Molothrus
Species:
M. rufoaxillaris
Binomial name
Molothrus rufoaxillaris
Cassin, 1866
Molothrus rufoaxillaris map.svg
Range of the screaming cowbird

The screaming cowbird (Molothrus rufoaxillaris) is an obligate brood parasite belonging to the family Icteridae and is found in South America. It is also known commonly as the short billed cowbird. [2]

Contents

Description

The screaming cowbird has mildly iridescent black plumage; the lesser under-wing coverts are rufous. The female is slightly duller in colour than the male. The legs are black and the iris is reddish brown. Adult body length is 18–21 cm and mean adult weight is 58 g for males and 48 g for females. [3] The call of the screaming cowbird was first described as "impetuous screaming notes"; [4] however, a more useful description for field identification is noisy, explosive and piercing with rasp-like calls also produced. [2] Screaming cowbirds are mostly seen in pairs or small flocks. [5]

Distribution and habitat

Within South America, the screaming cowbird is found in north east and central Argentina, south east Bolivia, central Brazil and throughout Paraguay and Uruguay. Its natural habitat is pastureland where it forages amongst grazing animals such as cows, hence the name "cowbird". Similar to other cowbirds, it forages predominantly on the ground, eating invertebrates that have been disturbed by grazing stock. The distribution of the screaming cowbird has increased significantly in recent decades due to habitat alteration caused by deforestation and by following its hosts into new areas. [2] [6] Both female and male screaming cowbirds show high fidelity in roosting locations. [7]

Reproduction

Host species

The screaming cowbird is a specialist brood parasite, predominantly parasitizing the nests of baywings (Agelaioides). [5] [8] [9] [10] In 1874, W H Hudson was first to observe this parasitic relationship when he witnessed what he believed to be baywing chicks morph into screaming cowbird plumage. [4] [8] [11]

The screaming cowbird also parasitizes the nests of the chopi blackbird (Gnorimopsar chopi) [12] [13] and the brown-and-yellow marshbird (Pseudoleistes virescens). [14] [15] [16] Parasitism of these other two species generally occurs in areas where baywings are absent but can also occur in its presence. [17] The three host species that can successfully raise screaming cowbirds are all cooperative breeders. [2] "Helpers" at the nest provide assistance with chick feeding and with predator defense. [18]

Parasite behaviour

Screaming cowbirds are monogamous and form stable pairs for the duration of the breeding season. [19] As obligate brood parasites, they do not build their own nests, and instead, parasitize the nests of other species, predominantly baywings.

Most baywing nests are parasitized by the screaming cowbird with parasitism rates of 74-100% recorded. [11] [17] [20] Parasitism rates of 5-20% have been recorded for the brown and yellow marsh bird [14] [15] and 46% for the Chopi blackbird. [17]

Screaming cowbird eggs are spotted like those of their main host, the baywing, but do vary in shape, background colour and markings. Although this may be obvious when they appear in the host nest during pre-laying, they can be difficult to detect in a nest full of eggs. [3] [8]

Screaming cowbirds can lay 6-20 eggs in a baywing nest but usually one pair will lay only 2 eggs in the host nest. Up to 12 female screaming cowbirds can parasitize the same baywing nest. [20]

Screaming cowbird adults frequently pierce the eggs of their hosts as well as previously laid parasite eggs. [21] One study found 22.5% of baywing eggs were punctured by the screaming cowbird. [11] Screaming cowbirds can distinguish between their eggs and those of other species and laboratory trials have shown that screaming cowbirds will puncture shining cowbird (Molothrus bonariensis) eggs more frequently than their own. [22] The purposes of egg puncture behavior are not clearly understood but may provide the parasite with information on the embryonic development of the host eggs and therefore whether or not to parasitize. Egg puncturing may also be practiced to reduce nestling competition and to enhance survival of parasitic offspring. [22] [23] Heavy predation in the form of egg punctures, which result in total nest failure and nest abandonment, may also create new opportunities for screaming cowbirds in the form of new nests to parasitize. [9]

Screaming cowbirds deceive their main host, the baywing, with superb visual chick mimicry. [10] [24] In fact, screaming cowbirds are the only avian brood parasite to exhibit this trait. [21] [25] There are slight differences in skin and bill colour of nestlings but this is only present for the first 4–5 days. They then remain almost identical in size and appearance until they become nutritionally independent.

Screaming cowbird chicks also mimic the begging calls of their baywing nest mates and, in addition, beg for longer and at a higher intensity. [26] This more intense begging does not reflect greater hunger demands; instead, reflects a hard-wired behavior to ensure adequate nourishment and survival. Although the rearing environment can influence begging call parameters, Screaming Cowbird nestlings develop the acoustic cues required for offspring recognition by the baywings independently of social experience. [27] Due to the mimicry of nestlings and fledglings, it has been suggested that screaming cowbirds and baywings are closely related; however, molecular research has shown the species are not each other's closest relatives. [21] [28]

Host response

The screaming cowbird frequently parasitizes its main host, the baywing, during the pre-laying period. [20] Screaming cowbirds lay 31% of their eggs before the first baywing egg but most of the eggs laid are ejected, and often within 24 hours. [29] By ejecting parasitic eggs with their feet, baywings can reduce the parasitic egg load by 75%. [30] Host species can eject an entire clutch and commence egg laying again in the same nest or abandon the nest and start afresh. [20] [30] Chopi blackbirds and brown and yellow marsh birds have not been observed to eject screaming cowbird eggs. [31]

The pre-laying period (the time between nest making and egg laying) of the baywing exhibits great variability in length (1–19 days). It is suggested that this behavior may act as an antiparasitic/defense mechanism to reduce the chances of successful parasitism. [29] Such behaviours are a fascinating element to the co-evolutionary arms race that exists between avian brood parasites and their hosts. [21] [25] [31]

Once hatched, baywings treat parasitic chicks as their own, not only by providing food and protection but also by removing ecto-parasites such as botfly larvae. [32]

Reproductive success

The main host, the baywing, can successfully fledge 1 screaming cowbird for 3 of its own. [2] Reproductive success, as the number of fledgling per egg laid, has been recorded to be 0.14 for the screaming cowbird when hosted by the baywing. [8] When hosted by the chopi blackbird, a reproductive success rate of 0.17 was found [17] In addition, the brown-and-yellow marshbird is also able to successfully rear screaming cowbird chicks. [14] [33]

The main host species, the baywing, clearly suffers losses through intense parasitism by the screaming cowbird; however, they are able to successfully raise their young with little overall impact in terms of hatching success, survival of nestlings and fledgling body mass. [11]

Related Research Articles

<span class="mw-page-title-main">Cuckoo</span> Family of birds

Cuckoos are birds in the Cuculidae family, the sole taxon in the order Cuculiformes. The cuckoo family includes the common or European cuckoo, roadrunners, koels, malkohas, couas, coucals, and anis. The coucals and anis are sometimes separated as distinct families, the Centropodidae and Crotophagidae, respectively. The cuckoo order Cuculiformes is one of three that make up the Otidimorphae, the other two being the turacos and the bustards. The family Cuculidae contains 150 species, which are divided into 33 genera.

<span class="mw-page-title-main">American coot</span> Species of bird

The American coot, also known as a mud hen or pouldeau, is a bird of the family Rallidae. Though commonly mistaken for ducks, American coots are only distantly related to ducks, belonging to a separate order. Unlike the webbed feet of ducks, coots have broad, lobed scales on their lower legs and toes that fold back with each step which facilitates walking on dry land. Coots live near water, typically inhabiting wetlands and open water bodies in North America. Groups of coots are called covers or rafts. The oldest known coot lived to be 22 years old.

<span class="mw-page-title-main">Brown-headed cowbird</span> Species of bird

The brown-headed cowbird is a small, obligate brood parasitic icterid native to temperate and subtropical North America. It is a permanent resident in the southern parts of its range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat around March or April.

<span class="mw-page-title-main">Hooded oriole</span> Species of bird

The hooded oriole is a medium-sized New World oriole. The male of this species ranges in color from a bright orange to a paler yellow, with a black back, face, tail and bib, with the wing containing two white bars. The female is more of an olive color with some yellow accents.

<span class="mw-page-title-main">Yellow warbler</span> Species of bird

The yellow warbler is a New World warbler species. Yellow warblers are the most widespread species in the diverse genus Setophaga, breeding in almost the whole of North America, the Caribbean, and down to northern South America.

<span class="mw-page-title-main">Grasshopper sparrow</span> Species of bird

The grasshopper sparrow is a small New World sparrow. It belongs to the genus Ammodramus, which contains three species that inhabit grasslands and prairies. Grasshopper sparrows are sometimes found in crop fields and they will readily colonize reclaimed grassland. In the core of their range, grasshopper sparrows are dependent upon large areas of grassland where they avoid trees and shrubs. They seek out heterogenous patches of prairie that contain clumps of dead grass or other vegetation where they conceal their nest, and also contain barer ground where they forage for insects, spiders, and seeds. Grasshopper sparrows are unusual among New World sparrows in that they sing two distinct song types, the prevalence of which varies with the nesting cycle. The primary male song, a high trill preceded by a stereotyped series of short chips, is reminiscent of the sounds of grasshoppers and is the origin of this species' name. Like some other birds of the central North American grasslands, this species also moves around a lot, not only via annual migrations, but individuals frequently disperse between breeding attempts or breeding seasons. Grasshopper sparrows are in steep decline across their range, even in the core of the breeding distribution in the tallgrass prairies of the central Great Plains. The Florida grasshopper sparrow is highly endangered.

<span class="mw-page-title-main">Carolina wren</span> Species of bird

The Carolina wren is a common species of wren that is a resident in the eastern half of the United States of America, the extreme south of Ontario, Canada, and the extreme northeast of Mexico. Severe winters restrict the northern limits of their range, while favorable weather conditions lead to a northward extension of their breeding range. Their preferred habitat is in dense cover in forest, farm edges, and suburban areas. This wren is the state bird of South Carolina.

<span class="mw-page-title-main">Asian koel</span> Species of bird

The Asian koel is a member of the cuckoo order of birds, the Cuculiformes. It is found in the Indian Subcontinent, China, and Southeast Asia. It forms a superspecies with the closely related black-billed koels, and Pacific koels which are sometimes treated as subspecies. The Asian koel like many of its related cuckoo kin is a brood parasite that lays its eggs in the nests of crows and other hosts, who raise its young. They are unusual among the cuckoos in being largely frugivorous as adults. The name koel is echoic in origin with several language variants. The bird is a widely used symbol in Indian and Nepali poetry.

<span class="mw-page-title-main">Brood parasitism</span> Subclass of parasitism, phenomenon that an animal relies on other inidivids to raise its young.

Brood parasitism is a subclass of parasitism and phenomenon and behavioural pattern of certain animals, brood parasites, that rely on others to raise their young. The strategy appears among birds, insects and fish. The brood parasite manipulates a host, either of the same or of another species, to raise its young as if it were its own, usually using egg mimicry, with eggs that resemble the host's.

<span class="mw-page-title-main">Cowbird</span> Genus of birds

Cowbirds are birds belonging to the genus Molothrus in the family Icteridae. They are of New World origin, and are obligate brood parasites, laying their eggs in the nests of other species.

<span class="mw-page-title-main">Giant cowbird</span> Species of bird

The giant cowbird is a large passerine bird in the New World family Icteridae. It breeds from southern Mexico south to northern Argentina, and on Trinidad and Tobago. It may have relatively recently colonised the latter island. It is a brood parasite and lays its eggs in the nests of other birds.

<span class="mw-page-title-main">Shiny cowbird</span> Species of bird

The shiny cowbird is a passerine bird in the New World family Icteridae. It breeds in most of South America except for dense forests and areas of high altitude such as mountains. Since 1900 the shiny cowbird's range has shifted northward, and it was recorded in the Caribbean islands as well as the United States, where it is found breeding in southern Florida. It is a bird associated with open habitats, including disturbed land from agriculture and deforestation.

<span class="mw-page-title-main">Bronzed cowbird</span> Species of bird in the Americas

The bronzed cowbird, once known as the red-eyed cowbird, is a small icterid.

An obligate parasite or holoparasite is a parasitic organism that cannot complete its life-cycle without exploiting a suitable host. If an obligate parasite cannot obtain a host it will fail to reproduce. This is opposed to a facultative parasite, which can act as a parasite but does not rely on its host to continue its life-cycle. Obligate parasites have evolved a variety of parasitic strategies to exploit their hosts. Holoparasites and some hemiparasites are obligate.

<span class="mw-page-title-main">Yellow-shouldered blackbird</span> Species of bird

The yellow-shouldered blackbird, known in Puerto Rican Spanish as mariquita de Puerto Rico or capitán, is a species of blackbird endemic to Puerto Rico. It has black plumage with a prominent yellow patch on the wing. Adult males and females are of similar appearance. The species is predominantly insectivorous.

<span class="mw-page-title-main">Horsfield's bronze cuckoo</span> Species of bird

Horsfield's bronze cuckoo is a small cuckoo in the family Cuculidae. Its size averages 22g and is distinguished by its green and bronze iridescent colouring on its back and incomplete brown barring from neck to tail. Horsfield's bronze cuckoo can be destiguished from other bronze cuckoos by its white eyebrow and brown eye stripe. The Horsfield's bronze cuckoo is common throughout Australia preferring the drier open woodlands away from forested areas.

<span class="mw-page-title-main">Forbes's blackbird</span> Species of bird

Forbes's blackbird is an endangered species of New World blackbird that is endemic to the Atlantic forest in South America. This species was named for the British zoologist William Alexander Forbes.

<span class="mw-page-title-main">Egg tossing (behavior)</span>

Egg tossing or egg destruction is a behavior observed in some species of birds where one individual removes an egg from the communal nest. This is related to infanticide, where parents kill their own or other's offspring. Egg tossing is observed in avian species, most commonly females, who are involved with cooperative breeding or brood parasitism. Among colonial non-co-nesting birds, egg-tossing is observed to be performed by an individual of the same species, and, in the case of brood parasites, this behavior is done by either the same or different species. The behavior of egg tossing offers its advantages and disadvantages to both the actor and recipient.

<span class="mw-page-title-main">Brood reduction</span>

Brood reduction occurs when the number of nestlings in a birds brood is reduced, usually because there is a limited amount of resources available. It can occur directly via infanticide, or indirectly via competition over resources between siblings. Avian parents often produce more offspring than they can care for, resulting in the death of some of the nestlings. Brood reduction was originally described by David Lack in his brood-reduction hypothesis to explain the existence of hatching asynchrony in many bird species.

References

  1. ↑ BirdLife International (2018). "Molothrus rufoaxillaris". IUCN Red List of Threatened Species . 2018: e.T22724342A132175624. doi: 10.2305/IUCN.UK.2018-2.RLTS.T22724342A132175624.en . Retrieved 13 November 2021.
  2. 1 2 3 4 5 Fraga, R. M. (2011). Family Icteridae (New World Blackbirds). In Handbook of the Birds of the World, vol 16: Tanagers to New World Blackbirds (J. del Hoyo,. A. Elliot, and D. A. Christie, Editors). Lynx Edicions, Barcelona, Spain. pp. 684-807
  3. 1 2 Davies, N. B. (2000). Cuckoos, Cowbirds and Other Cheats. Academic Press, London
  4. 1 2 Hudson, W. H.; Grönvold, Henrik (1920). Details - Birds of La Plata, by W. H. Hudson, with twenty-two coloured illustrations by H. Gronvold ... - Biodiversity Heritage Library. doi:10.5962/bhl.title.13416. hdl:2027/uc2.ark:/13960/t2m61dc1r.
  5. 1 2 Hoy, Gunnar; Ottow, Johann (1964). "Biological and Oological Studies of the Molothrine Cowbirds (Icteridae) of Argentina". The Auk. 81 (2): 186–203. doi:10.2307/4082768. JSTOR   4082768.
  6. ↑ Di Giacomo, Alejandro G.; Reboreda, Juan C. (2014). "Reproductive success of the specialist brood parasite Screaming Cowbird in an alternative host, the Chopi Blackbird". The Auk. 132 (1): 16–24. doi:10.1642/AUK-13-008.1. hdl: 11336/19670 . ISSN   0004-8038. S2CID   3953329.
  7. ↑ Scardamaglia, R.C.; Kacelnik, A.; Reboreda, J.C. (2018). "Roosting behaviour is related to reproductive strategy in brood parasitic cowbirds". Ibis. 160 (4): 779–789. doi:10.1111/ibi.12587. hdl: 11336/96594 .
  8. 1 2 3 4 de Mársico, María C.; Mahler, Bettina; Reboreda, Juan C. (2010-08-24). "Reproductive Success and Nestling Growth of the Baywing Parasitized by Screaming and Shiny Cowbirds". The Wilson Journal of Ornithology. 122 (3): 417–431. doi:10.1676/09-140.1. ISSN   1559-4491. S2CID   3964244.
  9. 1 2 de Mársico, María C.; Reboreda, Juan C. (2010-05-01). "Brood Parasitism Increases Mortality of Bay-Winged Cowbird Nests" (PDF). The Condor. 112 (2): 407–417. doi:10.1525/cond.2010.090118. hdl: 11336/68837 . ISSN   0010-5422. S2CID   51736285.
  10. 1 2 Fraga, R. M. (1979). "Differences between nestlings and fledglings of Screaming and Bay-winged cowbirds". Wilson Bulletin. 91: 151–154.
  11. 1 2 3 4 De Mársico, María C.; Reboreda, Juan C. (2014). "High frequency but low impact of brood parasitism by the specialist Screaming Cowbird on its primary host, the Baywing". Emu. 114 (4): 309–316. doi:10.1071/mu14008. hdl: 11336/31716 . S2CID   84190846.
  12. ↑ Fraga, R. M. (1996). "Further evidence of parasitism of Chopi Blackbirds (Gnorimopsar chopi) by the specialized Screaming Cowbird (Molothrus rufoaxillaris)". The Condor. 98 (4): 866–867. doi: 10.2307/1369874 . JSTOR   1369874.
  13. ↑ Mahler, B.; Sarquis Adamson, Y.; Di Giacomo, A. G.; Confalonieri, V. A.; Reboreda, J. C. (2009). "Utilization of a new host in the Screaming Cowbird Molothrus rufoaxillaris, a host specialist brood parasite: Host switch or host acquisition?". Behavioral Ecology and Sociobiology. 63 (11): 1603–1608. doi:10.1007/s00265-009-0755-0. S2CID   3941771.
  14. 1 2 3 Mermoz, Myriam E.; Reboreda, Juan C. (1996-08-01). "New Host for a Specialized Brood Parasite, the Screaming Cowbird". The Condor. 98 (3): 630–632. doi: 10.2307/1369576 . JSTOR   1369576.
  15. 1 2 Mermoz, M. E.; Fernandez, G. J. (2003). "Breeding success of a specialist brood parasite, the Screaming Cowbird, parasitizing an alternative host". The Condor. 105: 63–72. doi: 10.1093/condor/105.1.63 .
  16. ↑ Svagelj, Walter S.; Fernández, Gustavo J.; Mermoz, Myriam E. (2009-03-01). "Effects of nest-site characteristics and parental activity on cowbird parasitism and nest predation in Brown-and-yellow Marshbirds". Journal of Field Ornithology. 80 (1): 9–18. doi:10.1111/j.1557-9263.2009.00200.x. hdl: 11336/95899 . ISSN   1557-9263.
  17. 1 2 3 4 Di Giacomo, Alejandro G.; Reboreda, Juan C. (2014-10-01). "Reproductive success of the specialist brood parasite Screaming Cowbird in an alternative host, the Chopi Blackbird". The Auk. 132 (1): 16–24. doi:10.1642/AUK-13-008.1. hdl: 11336/19670 . ISSN   0004-8038. S2CID   3953329.
  18. ↑ Ursino, Cynthia A.; Mársico, María C. De; Sued, Mariela; Farall, Andrés; Reboreda, Juan C. (2011-08-18). "Brood parasitism disproportionately increases nest provisioning and helper recruitment in a cooperatively breeding bird". Behavioral Ecology and Sociobiology. 65 (12): 2279–2286. doi:10.1007/s00265-011-1238-7. hdl: 11336/68405 . ISSN   0340-5443. S2CID   20460496.
  19. ↑ Mason, P (1987). "Pair formation in cowbirds; evidence found for Screaming but not Shiny Cowbirds". Condor. 89 (2): 349–356. doi:10.2307/1368487. JSTOR   1368487.
  20. 1 2 3 4 Hoy, Gunnar; Ottow, Johann (1964-04-01). "Biological and Oological Studies of the Molothrine Cowbirds (Icteridae) of Argentina". The Auk. 81 (2): 186–203. doi:10.2307/4082768. JSTOR   4082768.
  21. 1 2 3 4 Davies, N. B. (2000). Cuckoos, Cowbirds and Other Cheats. Academic Press, London.
  22. 1 2 Llambías, Paulo E.; Ferretti, Valentina; Reboreda, Juan C. (2006-11-01). "Egg Discrimination and Sex-Specific Pecking Behaviour in Parasitic Cowbirds". Ethology. 112 (11): 1128–1135. doi:10.1111/j.1439-0310.2006.01272.x. ISSN   1439-0310.
  23. ↑ Massoni, Viviana; Reboreda, Juan Carlos (1998-04-01). "Costs of brood parasitism and the lack of defenses on the yellow-winged blackbird - shiny cowbird system". Behavioral Ecology and Sociobiology. 42 (4): 273–280. doi:10.1007/s002650050439. ISSN   0340-5443. S2CID   24499964.
  24. ↑ Mársico, María C. De; Gantchoff, Mariela G.; Reboreda, Juan C. (2012-09-07). "Host–parasite coevolution beyond the nestling stage? Mimicry of host fledglings by the specialist screaming cowbird". Proceedings of the Royal Society of London B: Biological Sciences. 279 (1742): 3401–3408. doi:10.1098/rspb.2012.0612. ISSN   0962-8452. PMC   3396896 . PMID   22648157.
  25. 1 2 Kruger, O (2007). "Cuckoos, cowbirds and hosts: Adaptations, trade-offs and constraints". Philosophical Transactions of the Royal Society of London, Series B. 362 (1486): 1873–1886. doi:10.1098/rstb.2006.1849. PMC   2442387 . PMID   17827098.
  26. ↑ Lichtenstein, Gabriela (2001-06-01). "Selfish begging by screaming cowbirds, a mimetic brood parasite of the bay-winged cowbird". Animal Behaviour. 61 (6): 1151–1158. doi:10.1006/anbe.2000.1688. S2CID   53162808.
  27. ↑ Rojas Ripari, J.M.; Ursino, C.A.; Reboreda, J.C.; De Mársico, M.C. (2019). "Innate development of acoustic signals for host parent–offspring recognition in the brood‐parasitic Screaming Cowbird Molothrus rufoaxillaris". Ibis. 161 (4): 717–729. doi:10.1111/ibi.12672. S2CID   92159389.
  28. ↑ Lanyon, Scott M. (1992-01-03). "Interspecific Brood Parasitism in Blackbirds (Icterinae): A Phylogenetic Perspective". Science. New Series. 255 (5040): 77–79. Bibcode:1992Sci...255...77L. doi:10.1126/science.1553533. JSTOR   2876063. PMID   1553533.
  29. 1 2 De Marsico, M. C., and Reboreda, J. C. (2008). Differential reproductive success favours strong host preference in a highly specialized brood parasite. Proceedings of the Royal Society of London, Series B 275:24499-2506
  30. 1 2 Mársico, María C. De; Gloag, Ros; Ursino, Cynthia A.; Reboreda, Juan C. (2013-06-23). "A novel method of rejection of brood parasitic eggs reduces parasitism intensity in a cowbird host". Biology Letters. 9 (3): 20130076. doi:10.1098/rsbl.2013.0076. ISSN   1744-9561. PMC   3645041 . PMID   23485877.
  31. 1 2 REBOREDA, Juan C.; FIORINI, Vanina D.; MARSICO, María C. De (2013-01-01). "Antiparasitic defenses in hosts of South American cowbirds". Chinese Birds. 4 (1): 57. doi: 10.5122/cbirds.2013.0003 .
  32. ↑ Fraga, Rosendo M. (September 1984). "Bay-Winged Cowbirds (Molothrus badius) Remove Ectoparasites From Their Brood Parasites, the Screaming Cowbirds (M. rufoaxillaris)". Biotropica. 16 (3): 223–226. doi:10.2307/2388055. JSTOR   2388055.
  33. ↑ Mermoz, M. E.; Fernandez, G. J. (2003). "Breeding success of a specialist brood parasite, the Screaming Cowbird, parasitizing and alternative host". The Condor. 105: 63–72. doi: 10.1093/condor/105.1.63 .
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.